[PATCH] power management for NAND flash

Vitaly Wool
2005-09-12T11:18:52Z

Greetings,
the patch inlined below allows to suspend/resume NAND flash.
It's similar to what is implemented for NOR flashes in cfi_cmdset_0001.c/cfi_cmdset_0002.c.
It's based on 2.6.10 kernel but applies to the current CVS snapshot.

Best regards,
Vitaly

Index: linux-2.6.10/include/linux/mtd/nand.h
===================================================================
--- linux-2.6.10.orig/include/linux/mtd/nand.h
+++ linux-2.6.10/include/linux/mtd/nand.h
@@ -244,6 +244,7 @@
FL_ERASING,
FL_SYNCING,
FL_CACHEDPRG,
+ FL_PM_SUSPENDED,
} nand_state_t;

/* Keep gcc happy */
Index: linux-2.6.10/drivers/mtd/nand/nand_base.c
===================================================================
--- linux-2.6.10.orig/drivers/mtd/nand/nand_base.c
+++ linux-2.6.10/drivers/mtd/nand/nand_base.c
@@ -46,6 +46,8 @@
* perform extra error status checks on erase and write failures. This required
* adding a wrapper function for nand_read_ecc.
*
+ * 08-20-2005 vwool: suspend/resume added
+ *
* Credits:
* David Woodhouse for adding multichip support
*
@@ -153,7 +155,7 @@
#define nand_verify_pages(...) (0)
#endif

-static void nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state);
+static int nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state);

/**
* nand_release_device - [GENERIC] release chip
@@ -755,7 +757,7 @@
*
* Get the device and lock it for exclusive access
*/
-static void nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state)
+static int nand_get_device (struct nand_chip *this, struct mtd_info *mtd, int new_state)
{
struct nand_chip *active;
spinlock_t *lock;
@@ -778,7 +780,11 @@
if (active == this && this->state == FL_READY) {
this->state = new_state;
spin_unlock(lock);
- return;
+ return 0;
+ }
+ if (new_state == FL_PM_SUSPENDED) {
+ spin_unlock(lock);
+ return (this->state == FL_PM_SUSPENDED) ? 0 : -EAGAIN;
}
set_current_state(TASK_UNINTERRUPTIBLE);
add_wait_queue(wq, &wait);
@@ -2284,6 +2290,34 @@
}

/**
+ * nand_suspend - [MTD Interface] Suspend the NAND flash
+ * @mtd: MTD device structure
+ */
+static int nand_suspend(struct mtd_info *mtd)
+{
+ struct nand_chip *this = mtd->priv;
+
+ return nand_get_device (this, mtd, FL_PM_SUSPENDED);
+}
+
+/**
+ * nand_resume - [MTD Interface] Resume the NAND flash
+ * @mtd: MTD device structure
+ */
+static void nand_resume(struct mtd_info *mtd)
+{
+ struct nand_chip *this = mtd->priv;
+
+ if (this->state == FL_PM_SUSPENDED)
+ nand_release_device(mtd);
+ else
+ printk(KERN_ERR "resume() called for the chip which is not "
+ "in suspended state\n");
+
+}
+
+
+/**
* nand_scan - [NAND Interface] Scan for the NAND device
* @mtd: MTD device structure
* @maxchips: Number of chips to scan for
@@ -2642,8 +2676,8 @@
mtd->sync = nand_sync;
mtd->lock = NULL;
mtd->unlock = NULL;
- mtd->suspend = NULL;
- mtd->resume = NULL;
+ mtd->suspend = nand_suspend;
+ mtd->resume = nand_resume;
mtd->block_isbad = nand_block_isbad;
mtd->block_markbad = nand_block_markbad;